20 Terrific Facts About Sea Turtles

For decades, scientists had no idea where some sea turtles made their nests. A home movie from 1947 solved the mystery.
A green sea turtle swims in the waters off Maui.
A green sea turtle swims in the waters off Maui. / M Swiet Productions/Moment/Getty Images

Sea turtles live in waters all around the world (except for the planet’s extreme north and south regions) and live as long as 80 years. There are seven species of sea turtles, and six of them—green, hawksbill, Kemp’s ridley, leatherback, loggerhead, and olive ridley—are listed as endangered or threatened. The flatback, found only in the seas around Australia, is considered vulnerable by that country. Here are 20 other things you might not know about sea turtles.

1. Hawksbill sea turtles are named for their jaws.

Hawksbill turtles (Eretmochelys imbricata) have raptorlike jaws to reach hard-to-get-to places in coral reefs. Their favorite food is sponges.

2. Green sea turtles go for greens.

A green sea turtle in a seagrass meadow.
A green sea turtle in a seagrass meadow. / cinoby/Getty Images

Green turtles (Chelonia mydas), the only herbivorous sea turtles, eat a vegetarian diet of seagrass and algae. That’s how they acquire their greenish color.

3. Leatherbacks sea turtles are adapted for eating soft stuff.

Leatherbacks (Dermochelys coriacea) eat jellyfish and other soft-bodied animals and have stiff spines in their throats to help them swallow this slippery prey.

4. Olive ridley turtles have mass nesting parties.

Olive ridley turtles (Lepidochelys olivacea) practice nesting in large groups known as arribadas (“arrivals” in Spanish). While solitary olive ridley nesting has been documented in as many as 40 countries, this spectacular event is seen in only five: Mexico, Nicaragua, Costa Rica, Panama, and India. Arribadas can include as many as 200,000 individuals.

5. Nest temperatures determine the sex of sea turtle hatchlings.

Warmer temperatures mean more females, cooler ones more males. In a 2014 study published in Nature, which examined sea turtle rookeries in Cape Verde, scientists estimated “that light-colored [cooler] beaches currently produce 70.10 percent females whereas dark-colored [warmer] beaches produce 93.46 percent females.

6. A home movie solved a sea turtle nesting mystery.

For decades, scientists had no idea where Kemp’s ridley sea turtles (Lepidochelys kempii) nested. Then, at the 1961 meeting of the American Society of Ichthyologists and Herpetologists in Austin, Texas, biologists saw a home movie made in 1947 by Andres Herrera, a sportsman and naturalist. It showed at least 40,000 Kemp’s ridleys nesting on a beach on the northern Gulf coast of Mexico.

7. Kemp’s ridley turtles are now making their home in Texas.

To increase their population, a secondary nesting location was created for Kemp’s ridley sea turtles on Texas’s Padre Island National Seashore. Biologists collected over 20,000 eggs that had been laid at the Mexican site, transferred to Texas, where they were incubated and hatched; and released the hatchlings on Padre Island’s sandy beaches. In 1996, officials released 369 hatchlings; by 2013 that number had grown to 11,369.

8. Kemp’s ridley turtles suffered in the Deepwater Horizon oil spill.

Studies have indicated that the number of Kemp’s ridley turtles at the site of the 2010 Deepwater Horizon oil spill in the Gulf of Mexico were considerably higher than previously thought, and some scientists are concerned the Texas nesting population will continue to suffer because of it.

9. One threat to sea turtles has been mostly solved.

Sea turtle mortality in shrimp trawls (a.k.a. bycatch) was once a major problem in the Gulf of Mexico, but the introduction of improved Turtle Excluder Devices (TEDs) on trawl nets in the 1980s has drastically reduced the number of sea turtles killed.

10. Light could also prevent sea turtle bycatch.

Small-scale coastal gillnet fisheries, common in many countries, accidentally catch significant numbers of sea turtles, injuring or drowning them. But changing the type of bait or using ultraviolet (UV) light-emitting diodes can reduce the chances of capture, according to a 2013 study in the journal Biology Letters.

11. Sea turtles can dive deep and stay under for long periods.

A submerged hawksbill sea turtle with the sun shining through the water
A hawksbill sea turtle gets ready to dive. / Bernard Radvaner/Corbis/Getty Images

As reptiles, sea turtles breathe air, but they have the ability to remain submerged for hours at a time. Leatherback sea turtles can dive up to 3000 feet deep.

12. Sea turtles are long-distance swimmers.

Sea turtles have been documented migrating vast distances. One was tracked traveling more than 9000 miles from Baja California to Japan.

13. A dog was trained to sniff out hidden sea turtle nests.

While most sea turtle species nest at night, the Kemp’s ridley nests during the day, when winds quickly blow away the females’ tracks. This can make it difficult for Padre Island National Seashore staff to find nests so they can bring the eggs into a special lab to incubate. Dr. Donna Shaver, the seashore’s supervisory wildlife biologist, trained her Cairn terrier Ridley to sniff out nests. Other dogs have since been trained to find sea turtle nests in other locations.

14. To track sea turtle hatchlings, scientists use manicure supplies.

Scientists don’t know much about the early stages of sea turtle life. Given a hatchling’s small size and rapid growth, the usual ways of attaching tracking tags don’t work. But researchers found that a neoprene-silicone attachment on an acrylic base coat—just like that used for fake fingernails—kept tags on for an average of 70 days, long enough to clear up a lot of the mystery of those lost years [PDF].

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15. Scientists pulled off a massive sea turtle egg evacuation.

After the Deepwater Horizon oil spill, scientists were concerned that sea turtles hatching on the Gulf beaches of Alabama and northern Florida would swim out into deadly oil. They launched a massive relocation effort, moving 28,000 eggs between June 25 and August 18 of that year to Kennedy Space Center on Florida’s east coast. (The eggs were shipped by FedEx.) The rescue succeeded; in July, August, and September, 14,000 hatchlings—mostly loggerheads—were released into the Atlantic Ocean.

16. Sea turtles are still threatened by poaching.

Poaching remains a significant threat to sea turtles around the world. Scientists have begun using fake sea turtle eggs to track poaching—they put decoy eggs outfitted with tracking chips into real turtle nests, allowing researchers to track the locations of the stolen eggs.

17. Sea turtles get tumors.

Fibropapillomatosis is a chronic and often lethal tumor-forming disease in sea turtles. Recent research suggests that FP occurs more frequently in green sea turtles that forage in waters subject to eutrophication, or an increase in organic nutrients that leads to algal blooms and excessive vegetation which sucks oxygen out of the water. Stormwater run-off and other human activities contribute to eutrophication.

18. Sea turtles eat a lot of plastic.

A leatherback sea turtle on the beach in Trinidad.
A leatherback sea turtle on the beach in Trinidad. / Mark Meredith/Moment/Getty Images

Plastic debris in the ocean poses a significant threat to sea turtles, with a 2013 study showing that leatherback and green sea turtles are at the greatest risk of becoming sick or dying from eating plastic. A 1993 study found plastic debris in the digestive tracts of 51 percent of loggerheads, and necropsies of dead turtles have found some with their entire digestive tracts packed with pieces of plastic bags.

19. Volunteers help save sea turtles.

Sea turtle conservation projects around the world rely on volunteers to help patrol nesting beaches, move eggs into protected corrals, and monitor the release of hatchlings. Volunteers generally commit for at least two weeks, stay in tents or cabins, and enjoy communal meals.

20. Sea turtles use Earth’s magnetic field to navigate.

A female sea turtle returns to the beach where she hatched when it is time to lay her own eggs. Some species travel vast distances in the 10 to 20 years between hatching and first nest. Scientists generated magnetic fields in the lab and demonstrated that sea turtles have the ability to detect Earth’s magnetic field and use it as an orientation cue.

A version of this story was published in 2021; it has been updated for 2024.